Java Utililty Methods Collection Convert

List of utility methods to do Collection Convert

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Description

The list of methods to do Collection Convert are organized into topic(s).

Method

StringtoDelimitedString(final Collection coll, final String delim)
Convenience method to return a Collection as a delimited (e.g. 
return tooDelimitedString(coll, delim, "", "");
ListtoDoubles(Collection numbers)
to Doubles 
List<Double> result = new ArrayList<Double>();
for (Number number : numbers) {
    result.add(number.doubleValue());
return result;
EnumerationtoEnumeration(final Collection collection)
to Enumeration 
return Collections.enumeration(collection);
StringtoEscapedStringWithDelimiters(Collection objects, String delim)
to Escaped String With Delimiters 
StringBuffer buffer = new StringBuffer();
int index = 0;
for (Object obj : objects) {
    if (index++ > 0)
        buffer.append(delim);
    String string = obj.toString();
    if (string.startsWith("\"") && string.endsWith("\"")) {
        if (string.length() <= 2)
...
booleantoggleEntry(T entry, Collection collection)
Toggles an entry in a collection. 
if (collection.remove(entry)) {
    return false;
} else {
    collection.add(entry);
    return true;
SettoHashSet(Collection c)
to Hash Set 
if (isEmpty(c)) {
    return null;
Set<T> set = new HashSet<T>(c.size() * 2);
set.addAll(c);
return set;
StringtoHtml(Collection collection)
to Html 
StringBuffer sb = new StringBuffer();
sb.append("<ul>");
Iterator iterator = collection.iterator();
while (iterator.hasNext()) {
    sb.append("<li>");
    sb.append(iterator.next());
    sb.append("</li>");
sb.append("</ul>");
return sb.toString();
CollectiontoIntegerCollection(int[] ints)
to Integer Collection 
ArrayList<Integer> ret = new ArrayList<Integer>();
for (int i : ints)
    ret.add(new Integer(i));
return ret;
StringtoJSONString(Collection collection)
to JSON String 
if (collection == null) {
    return null;
} else {
    StringBuilder sb = new StringBuilder();
    sb.append('[');
    for (Object item : collection) {
        if (item == null) {
            sb.append("null");
...
StringtokenSetString(Collection tokens)
token Set String 
String string = String.join(", ", addNewLines(tokens));
if (tokens.size() < 5) {
    return string;
} else {
    return "\n" + string + "\n";